Process for making brake segments



Patented Nov. 17, 192s."v

UNITED STATES PATENT OFFICE- rznnoza .1'. NOVAK, .or- BRIDGEPORT, comvncrrour,

f COMPANY, OF BRIDGEIPORT, CONNECTICUT, A CORPORATION OF CONNECTICUT.-

BROCESS FORMAKING BRAKE SEGMENTS.

1Tb Drawing.

To all whom itimag concern Be it known that I, IZADOR .J. NovAK, a

citizen of the United States, and a resident of the city of Bridgeport, county of Fanfield, and State of Connecticut, have inventby dispensing with the necessity of having;

separate curved molds for all sizes of the segments.

The use of curved brake segments of molded-friction material for brakes, and similar devices where frict onal resistance s applied to a rotatingscurved. surface has come into prominence due to the 'fact that'they exhibit exceptionally low wear because of their high denslty, and consequently requ re very little care or adjustment. It is almost universal practice among th higher class of foreign automobiles, and also .in connection with heavy stationary machinery to use brakes lined with molded curved segments of frictional material. In fact the molded segments have almost entirely super-v seded the flexible woven type of brake lining in connection with heavy machinery in manufacturing, transportation machinery, and in innumerable other uses.

lines a great quantityof molded friction resistance substances is used. 7

This material has heretofore been made by the use of heat and pressure in a mold which was substantially machined to produce the correct curvature and thickness. This necessitates the manufacture of a distinct and individual mold for each different width, thickness and curvature desired, and; to produce the 'difierent sizes'of mold segments at. present used industrially, .a very expensive stock of molds is necessary These molds are very expensive, andas a uence, a considerable amount of capital is invested in the moldsthemselves.

Byethe method hereinafter explained, it

has en found ractical to dispense with all In these of the fibres.

Application filed October 21, 1922. SeriaLNo. 596,153.

curved molds by proper selection and manipulation of the binder material. In order to utilize this method, itis essential that the binder material be highly thermo plastic, and that it is of such composition that it will set by the action of heat to a mater al having very low thermo plasticqualitie s. Certain of the phenol resin condensation products have this property after their I initial setting. There are also various combinations of phenol resins, varnish gums and like substances which have these desirable properties; The details of this method follow.

In the first place, there is made up by any convenient means a composition of asbestos or other fibre, and a sufiicient proportion of the thermo plastic material previously mentioned to act as a binder. This may be woven asbestos tape saturated with a solution of the thermo plastic substance and the solvent removed by drying, or a homogeneousmixture of loose asbestos fibre and liquid binder material, the binder ma-y terral'in 'eachcasetaking the form of the thermo plastic substances mentioned.

Thecomposition is then set in suitable long fiat molds under heavy hydraulic pressure at about 350 F., for a time sufficient to compact it as closely as desired, and flow the binder material uniformly through the fibre, This operation is a relatively short one and presses the material into dense flat strips of any desired length, width 7 and thickness.

that the cost of molds for flat oblong pieces AssIeNon To THE nAYBn s'ros It will be readily appreciated is much lower than the cost ot the molds producing a'curved contour. 7 Also, a single mold may produce segments for a brake drum of any diameter. The

device until, due to the thermo plastic nature of the binder they may be bent through a limited are without distortion or parting The exact temperature is naturally variable for the different binders, and the amounts of the binder in the various stocks will likewise be factors which will control to some extent the temperature necessary to make the segments malleable.

When the fiat strip is sufliciently plastic. it is run through a set of forming rolls adjustable to be set at variable distances from 9.5 strips are now out to the required developed I length for the curved segment desired.

They are heated on a steam table or other one another, such as used for bendin metal in an arc. These forming rolls are rst set to give the curvature desiredJ -When the piece has been bent or curved. it is placed in an oven at an elevated temperature and baked untilit is no, longer therm'ovplastic.

, This operation may take from five to ten 1 hours at temperatures in excess of 3009 in. order to get the curved segments into desired condition. a

Affurther advantage of this method. is the fact that wide, flat slabs of this material in any thickness maybe kept in stock, indefinitely, and on order a'ny size may be sawed ofi, 'andwshaped in' ashort period of time,- thus eliminatin the necessity. of having on hand innumerable shapesf'or the different types of brake segmentsfi" thermo plastic composition for use as binder, Lhavetake'n equal parts of phenol resinand sandarac ('a gum) and dissolved these together in alcohol and As an example of a i used as a saturant for woven asbestos tape such as made from asbestos covered wire. Preferably the tape is saturate while the. binder isirr heatedcondition and then after saturation the tape is dried to remove the alcohol, there bein then left substantially one part of binder y weight to five parts of tape by weight. After drying, the tape is laced in a flat mold and compressed to the esir'ed thickness. This mold is heated to- 350 'F.,' and the mass compressed for say 400 F., andwhile so Lerties, forming the; b1

'ture and'then curing e same to make the ten .-minutes. This is sufficient to flow and set the binder-partially without causingit to lose any ofitsthermo plastic properties.

- It is then removed from the mold, out

into 7 lengths,

dition's, subjeetin the saturated b ank to an.

initial treatment by hot presses, then. while the binder Stlll possesses thermoplastic propto desired curvabinder infusible.

2. A process of making :curvedfrictionelements consisting in making a composition of fibrous material and a fusible binder capable of having thermolastic properties under given conditions, su jecting the compositionto an initial treatment under-"heat and pressure, then while, the binder ,still ossesses thermo-plastic properties, formi'ngthe composition to desired curvature and then curing to make the binder infusible.

3.'A process of making'curved friction elements consisting in making. acompost, tron- 0f an .1ncombust1ble fibrous material-- and a fusible binder capable of having .thermo-plast-ic properties under given con-' dll51QIlS,- subjecting .the composition to an initial treatment under heat and pressure; I I

thenfwhile the binder still possesses thermofl; plastic properties, forming the. composition todesiredcurvature and then curing they same to make the binder infusible.

4." A process for making curved friction eletainin a binder thermo-plasticnnder' given condit ons, termined curvature by rolling, rendering said binder nonthermo plastic.

5. A process of making curved friction; elements consisting in maklng a composition.

of fibrous material and a fusible binder capable of having thermo-plastic properties under given conditions, su jecting the comforming the slabs-to a predeand then ments consistingin producing flat slabs con- A position to an initial treatment under heat and pressure, then while the binder still possesses thermo-plastic properties, forming the blank to desired curvature," and then curing. p 6. A process of making curved friction elements consisting in saturating fibrous material with a fusible binder having thermoplastic properties, fibrous composition "substantial portion of its thermo-plastic' properties,

in then forming thefibrons composition to subjecting the saturated. to an initial heat and. ressure treatment to cause the binder to ow and setfp'artially without losing; any

desired curvatures and in then,

curing the curved product to make the binder nonther-mo-plastic.

7. A process for making curved friction elements consisting in (producing. flat slabs containing a binder thermo-plastic under given conditions, forming tl1e slabs to a predetermined curvature by rolling and then rendering said binder non-thermd'pl'astic, without substantial distortion or parting of the fibres a izanoa J. rovaKl 4 

